Disclosed herein is an apparatus and method that adjusts a printer fuser nip.
Presently, image output devices, such as printers, multifunction media devices, xerographic machines, ink jet printers, and other devices, produce images on media sheets, such as paper, substrates, transparencies, plastic, cardboard, or other media sheets. To produce an image, marking material, such as toner, ink jet ink, or other marking material, is applied to a media sheet to create a latent image on the media sheet. A fuser assembly then affixes or fuses the latent image to the media sheet by applying heat and/or pressure to the media sheet.
Fuser assemblies apply pressure using rotational members, such as fuser rolls or belts, that are coupled to each other at a fuser nip. Pressure is applied to the latent image on the media sheet as the media sheet is fed through the fuser nip. Unfortunately, repeated contact between the media sheet edges and a rotational fuser member result in worn areas, also known as edge wear, on the fuser member. The worn areas eventually manifest as differential gloss bands on resulting prints after fusing many sheets of one sheet width followed by fusing sheets of a larger sheet width. For example, a differential gloss band appears on 14″ wide media sheets after running a large number of 11″ wide media sheets. As it turns out, fuser run cost is a large part of the overall printer marking engine run cost, and edge wear is a leading cause of fusing failure regardless of print engine type, such as mono or color, or market segment, such as office or production. The edge wear occurs in both inboard and outboard areas on fusing members, where the level of wear in either area can dictate edge wear life.
Currently, the width of a fuser nip is fixed after fuser assembly installation regardless of paper type or fuser roll modulus. Also, current protocol for setting the fuser nip width requires the machine operator or service technician to first, insert a media sheet of a given size and type the fusing nip; second, engage and then disengage the fuser rolls; third, remove and dust the sheet with chalk powder where the powder will stick to the fuser oil that was transferred to the sheet when the fuser rolls were engaged; fourth, measure the resulting nip width impression on the sheet at specified inboard and outboard locations; fifth, adjust the inboard and outboard loads on the pressure roll as needed; and sixth repeat the first five steps until the nip width is within a desired specification. Obviously, the manual approach is time consuming and can be difficult. Also, because the fuser roll hardness can vary from roll-to-roll, fuser nip characteristics vary when the technician does not properly reset the fuser nip after installing a new fuser assembly or roll. Further edge wear and fuser problems occur when technicians do not correctly and consistently follow the proper procedures.
From an edge wear viewpoint, studies indicate that the current specifications for the fuser nip width and roll hardness are not adequate, especially because the specifications are traditionally dictated by fix, gloss, and stripping requirements and not by fuser edge wear. Tightening the spec on the manual nip setting process is not practical. Similarly, demanding a tighter spec on roll hardness is also not feasible.
Thus, there is a need for an apparatus and method that adjusts a printer fuser nip.